So, to sum up your argument, we've become weak, hedonistic, and uncaring about our own civilization.
"We" are no different than our great grandparents or their great grandparents. What has changed is the environment, and it would have effected them the same way.
What you call "weak", others people call "wealthy".
What you see "hedonism", others see agency and self-determination.
And the only people who ever spend time fretting about "our own civilization" are people who are unhappy with it and want it to change.
I'd also note you seem to have so internalized the "exponential growth forever" belief that you can't even see it. The earth's carrying capacity is not infinite, as we're learning a bit more every day. I'm absolutely not some Elifist or similar, but it is simply true, and those who profess to care deeply about "civilization" need to confront it if they want to be taken seriously.
And while abstractly there's no inherent political valence here, in this world these beliefs are mostly professed by authoritarian-natalists whose program is also wrapped around eugenics and really shitty racial beliefs as well as regressive beliefs about rights (especially those of women) and social control. I don't know if you're in that category or not, but that's a really ugly path to be treading.